This invention relates to a digital video signal processing apparatus, and more particularly, to a digital non-addition mixing apparatus. A non-addition mixing (NAM) apparatus is adapted to receive a plurality of video signals and to output the signal having the highest amplitude.
A prior art digital non-addition mixing apparatus is composed of unit circuits, each receiving two digital video signals and including a comparator and a selector for selecting one higher level video signal in response to the output of the comparator. In the prior art digital non-addition mixing apparatus, such a unit circuit is connected in a tournament form if the number of input digital video signals to this non-addition mixing apparatus is increased to more than two. However, in circuits constructed in the tournament form, the required number of unit circuits is determined by the number of the input digital video signals. When the number of input digital video signals increases, the circuit configuration of the prior art apparatus becomes more complicated. Moreover, the signal processing time also increases greatly.